1. Technical Field
The present invention relates to a line head and an image forming apparatus having the same.
2. Related Art
An image forming apparatus has been used to form an image on a recording medium (for example, refer to JP-A-9-307697).
An image forming apparatus disclosed in JP-A-9-307697 includes a microlens array, a light-emitting element array that is provided at a light-incident surface side of the microlens array and emits light toward the microlens array, and a photoconductor that is provided at a light-emitting surface side of the microlens array and has a light receiving surface (imaging surface) which receives light from the microlens array. The microlens array is configured to include a plurality of microlenses and supporting members (holding members) that support the microlens. In addition, a light-incidence-side surface and a light-emission-side surface of each of the microlenses are convex surfaces. That is, each of the microlenses is formed as a biconvex lens.
In the image forming apparatus having such a configuration, the microlens array and the light-emitting element array are arranged opposite each other with a gap therebetween, and a space (hereinafter, this space is called an ‘inner space’) is formed between the microlens array and the light-emitting element array. In the inner space, an airtight state is normally maintained by a casing (fixing member) that fixes the microlens array and the light-emitting element array thereto. Accordingly, it is prevented that dust, dirt, toner particles, and the like (hereinafter, collectively called ‘foreign matters’), which contaminate a light-incidence-side surface of the microlens array, enter into the inner space.
In addition, a space (hereinafter, this space is called an ‘outer space’) is also formed between the microlens array and the photoconductor (light receiving surface). The outer space communicates with the outside (room where the image forming apparatus is used) of the image forming apparatus. For this reason, when outside (indoor) air enters into the image forming apparatus, the air reaches the outer space and foreign matters included in the air adhere to a light-emission-side surface of the microlens array. As described above, the light-emission-side surface of each microlens is a convex surface. Accordingly, there has been a problem that a concave portion (recess) is formed between adjacent convex surfaces and the adhered foreign matters are accumulated in the recess. It is difficult to remove the accumulated foreign matters. Furthermore, in the microlens array to which the foreign matters adhere, light is blocked or scattered due to the foreign matters. Accordingly, there also has been a problem that a clear image is not formed on a photoconductor since the amount of light to be irradiated onto the photoconductor is not sufficient or a portion of the photoconductor to be exposed is not properly exposed due to scattered light or the like.